GB2054693A

GB2054693A - Lintel

Info

Publication number: GB2054693A
Application number: GB8015696A
Authority: GB
Original assignee: SEVERNWISE Ltd
Current assignee: SEVERNWISE Ltd
Priority date: 1979-05-11
Filing date: 1980-05-12
Publication date: 1981-02-18
Also published as: GB2054693B

Abstract

A lintel has a first angle section (1) having a lateral flange (5) and an upwardly-extending panel (6, 7), and a second angle section (2) having a lateral flange (9) and an upwardly- extending panel (10). The angle sections (1, 2) are secured together by interlocking portions (8) and (11) of the first angle section (1) and second angle section (2) respectively. <IMAGE>

Description

SPECIFICATION Lintel This invention relates to lintels suitable for use over apertures in cavity walls for supporting the inner and outer leaves of the cavity wall above the aperture. In the following description and claims, where the terms "laterally", "upwardly", "upper" "lower" and like terms are used to define the relative location of different parts of the lintel, they refer to the orientation of those parts of the lintel when the lintel is in use.

One known type of lintel comprises a box section disposed under an inner leaf of a cavity wall and a laterally extending flange disposed under the outer leaf of the wall. Such a lintel is constructed from several components which are welded together. There is thus always the danger of such a lintel failing due to one or more defective welds. Furthermore, the box section replaces up to 3 courses of brickwork in the inner leaf, and as a consequence can severely impair the thermal insulation qualities of a cavity wall.

Another type of lintel known as the "top hat" lintel comprises two laterally extending flanges, which support the two leafs of a cavity wall, and two interconnected upwardly extending sides which are disposed in the cavity. As this lintel is made from a single metal sheet, it provides a thermal bridge between the two leaves. However, although the outer leaf of a cavity wall may support only half the load supported by the inner leaf, both sides of a "top hat" lintel will be equally strong because the lintel is made from a single sheet of material. It is thus not possible to economise on material and reduce the weight of the lintel by making the portion which is to support the outer leaf from thinner gauge material than the portion which is to support the inner leaf.

According to the present invention there is provided a lintel suitable for use over an aperture in a cavity wall comprising two spaced leaves, which lintel comprises first and second angle sections, each of which comprises a lateral flange for supporting, in use, a portion of a respective leaf of the cavity wall above said aperture, each angle section further comprising an upwardly-extending panel, the two panels having portions which interlock with one another to secure the angle sections together.

Advantageously, the upwardly-extending panel of the first angle section comprises a lower region, extending substantially vertically from the flange of the first angle section, and an upper region which includes the interlocking portion of that angle section, the upper region being inclined by an obtuse angle to the lower region towards the second angle section.

Advantageously, the external surface of one of the interlocking portions substantially corresponds to the internal surface of the other interlocking portion.

Preferably the lintel includes a plurality of blocks disposed between lower regions of the said first and second angle sections, which blocks maintain a constant spacing between the angle sections.

The first and second angle sections can be made from steel which may be galvanised.

The lintel can include keying means for plaster, mortar or cement, which means can comprise metal lathing or mesh secured to the blocks or to the laterally-extending side of one of the angle sections. The keying means may comprise holes in the laterally-extending side of at least one of the angle sections.

The present invention also provides a method of building a cavity wall having an aperture therein, the method comprising building up inner and outer leaves of the cavity wall on both sides of the proposed aperture, mounting thereon a lintel according to the present invention so that one of the angle sections is supported by its lateral flange on the outer leaf of the wall and the other angle section is supported by its lateral flange on the inner leaf of the wall, and then building up the outer and inner leaves over the aperture on the first and second angle sections.

For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 shows a section through a first embodiment of a lintel when in use in a cavity wall; Figure 2 shows a side view of the lintel of Figure 1; Figure 3 shows an end view, similar to that of Figure 1, of a block forming part of the lintel shown in Figures 1 and 2; Figure 4 shows a side view of the block on Figure 3; Figure 5 shows a plan view of the block of Figures 3 and 4; Figure 6 shows part of a section through a second embodiment of the lintel; and Figures 7 to 14 show further lintel constructions.

Referring to Figure 1, the lintel comprises a first angle section 1 and second angle section 2 which are formed from galvanised steel. The first angle section 1 supports a portion 3 of an outer leaf of a cavity wall above an aperture in the wall and the second angle section 2 supports a corresponding portion 4 of an inner leaf of the cavity wall. The ends of the angle sections 1 and 2 are supported on the portions of the outer and inner leaves of the cavity wall which define sides of the aperture and which are not shown in the Figures.

The first angle section 1 has a lateral, generally horizontal, flange 5, on which the portion 3 of the outer leaf is supported, and an upwardlyextending panel which comprises a lower region 6, extending substantially vertically from the side 5, and an upper region 7 which is inclined at an obtuse angle to the lower region 6 so that it slopes towards the angle section 2. The upper region 7 ends at a curvilinear portion 8 which in this embodiment comprises, in section, an arc of a circle, the axis of the curvilinear portion being parallel to the axis of the first angle section 1. The second angle section 2 similarly comprises a lateral, horizontal, flange 9 and an upwardly extending panel 10.The panel 10 ends at a curvilinear portion 11 which again comprises, in section, an arc of a circle, the axis of the curvilinear portion 11 being parallel to the axis of the second angle section 2. The internal radius of the curvilinear portion 11 is substantially equal to the external radius of the curvilinear portion 8 so that the curvilinear portions 8 and 11 can interlock with one another as shown in Figure 1 with their adjacent surfaces in contact.

In order that the lower portions of the angle sections 1 and 2 are spaced apart from one another, blocks 12 are provided at regular intervals along the length of the lintel. Each block 12 has two recesses 1 3 and 14 (see Figure 5) on opposite side faces thereof. These recesses 13 and 14 correspond to recesses 15 and 16 formed in the first and second angle sections 1 and 2. A bolt or rivet 1 7 passes through openings 1 8 and 19 in the angle sections 1 and 2 and through a bore 20 in the block 12 to clamp the block 12 between the angle sections 1 and 2. Figures 3, 4 and 5 show the detailed construction of each block 12. The curvilinear portions 8 and 11 and the blocks 12 fix the angle sections rigidly together.The blocks 12 may be replaced by an uninterrupted batten turning the length of the lintel.

The curvilinear portions 8 and 11 provide resistance to buckling of the upwardly-extending sides of the angle sections 1 and 2. The curvilinear portions 8 and 11 also enable shear stresses in a plane perpendicular to the axes of the angle sections 1 and 2 to be transferred from one angle section to the other. This latter feature can be important in cavity walls as the load on the angle sections 1 and 2 may not be equal. The inner leaf of the cavity wall frequently applies a greater load to the lintel than the outer leaf, as loads on floors and roofs are generally applied to the inner leaf only; the inner leaf, for example, may apply to the lintel two thirds of the total load on the lintel.If there is a substantial difference between the loads applied by the inner and outer leaves to the lintel, the angle sections 1 and 2 can be made from steel of different gauge, the gauge of each section being chosen to correspond to the load on that section.

The outer leaf of the cavity wall may be constructed in known manner using bricks 21 and mortar 22 and the inner leaf can comprise blockwork 23. The lowermost course of bricks 21 above the aperture bedded on the angle sections 1 by a further layer of mortar 22. The outer leaf is further separated from the angle section 1 by a damp proof course 24.

The dimensions of the lintel can be chosen so as to match the size of the aperture and the load imposed upon the lintel by the portions 3 and 4 of the cavity wall. For normal housebuilding, the lintel will need to fit into a 50 mm cavity defined by inner and outer leaves which are 100 mm thick.

The lintel can be in lengths from 900-3000,mm with the blocks 1 2 at 250 mm centres. The blocks 12 preferably comprise glass reinforced concrete or poly(vinyl chloride) but could be made from timber, steel or other suitable materials.

In order to prevent, or at least discourage, the.

intrusion of water through the wall, the flange 5 of the first angle section 1 has a downturned edge 25 and the flange 9 of the second angle section 2 has an upturned edge 26. The downturned and upturned edges 25 and 26 also serve to stiffen the flanges 5 and 9 respectively.

The dimensions of the curvilinear portions 8 and 11 can be such that, during assembly of the lintel, the portion 8 is hooked into the portion 11 and the whole of the portion 8 is then engaged with the portion 11 by relative rotation between the angle sections 1 and 2. Alternatively, the two angle sections 1 and 2 can be interlocked by sliding the portion 8 longitudinally into the portion 11, or by a combination of longitudinal sliding and rotation.

The flange 9 of the angle section 2 can also include a plurality of holes 27 (Figure 1) to provide a key for plaster 28 which can then be applied directly to the angle section 2. Alternatively, the holes 27 may be used to secure metal lathing or mesh, or plasterboard, to the flange 9 by plastics buttons or similar fixtures. If metal lathing or mesh is secured to the angle section 2, the plaster is then held by the iathing or mesh in known manner. The holes 27 can be in the form of slots which are parallel to the axis of the angle section 2. The size and disposition of the holes 27 should be selected so that the strength of the lintel with regard to vertical loads is not affected to any great extent.

Figure 6 shows an alternative embodiment of the curvilinear portions 8 and 11. In this embodiment, the curvilinear portions 8 and i 1 are approximately spiral and enable a "snap fit" to be obtained between the two curvilinear portions 8 and 11, i.e. when the portion 8 is inserted in the portion 11 and then rotated, there is initially a moment opposing that rotation but, once the portion 8 has been rotated through a sufficient angle relative to the portion 11, the moment is reversed and aids the rotation of the portion 8 so that, when the portions 8 and 11 are fully interlocked they are also securely fastened together.

Seven further lintel constructions are shown in Figures 7-14. For simplicity only the two angle sections 1 and 2 are shown in these Figures, except for Figure 10 which also shows a longitudinally-extending wooden batten and metal mesh for keying pilaster. All the embodiments of the lintel, when compiete, are intended to include a wooden batten or the like for spacing the two angle sections 1 and 2, as shown in Figure 10.

Preferably the interlocking portions of the two angle sections 1 and 2 are such as to bias the lower end regions of the lintels 1 and 2 together.

They then must be forced apart before the wooden batten can be inserted, thus ensuring that the wooden batten is gripped and held in place by the angle sections 1 and 2.

With reference to Figure 7, as in the first embodiment, the first angle section 1 includes a lower region 6 which is substantially vertical and an upper region 7 which is inclined at an obtuse angle to the lower region 6. The upper region 7 continues into a short vertically-extending first part 40, which in turn is connected to a short horizontal second part 41 which extends away from the vertical panel 10 of the second angle section 2. From the upper end of the vertical panel 1 0, a first part 42 of the second angle section 2 extends downwards and away from that side 10 so that an acute angle is included between the first part 42 and the side 10. The part 42 continues into a horizontal second part 43 which extends back towards the panel 10.The first part 41 is disposed above the part 43, and this arrangement serves to lock the two angle sections 1 and 2 together.

In the embodiment shown in Figure 8 the first angle section 1 is identical to that shown in Figure 7. However, the second angle section 2 differs in that the part 43 of Figure 7 is replaced by a part 50 which is approximately at a right angle to the first part 42. This second part 50 extends downwards and towards the panel 10. The second part 41 of the first angle section 1 is now disposed in a triangular cavity defined by the parts 42 and 50 and an upper end region of the panel 10. The free end of the second part 41 abuts the junction between the parts 42 and 50, whilst the first part 40 abuts the panel 10, as in the Figure 7 embodiment.

The embodiment shown in Figure 9 uses a first angle section 1 which is identical to that used in the previous two embodiments. In this embodiment, the second angle section 2 has a horizontally disposed first part 55 extending away from the panel 10, which turns through an angle of 1 800 to continue as a horizontal second part 56 extending back towards the panel 10. These two parts 55 and 56 define a horizontally disposed slot in which the second part 41 of the first angle section 1 is located to lock the two angle sections 1 and 2 together.

In the embodiment shown in Figure 10, the second angle section 2 is similar to that in the embodiment shown in Figure 8. The upper region 7 of the first angle section 1 continues as a vertically extending first part 60. This verticallyextending first part 60 then turns through an angle of greater than 900 to continue as a second part 61 which extends downwards and away from the panel 10. The angle between the first and second parts 60 and 61 is the same as that between the parts 42 and the panel 10 of the second angle section 2, so that the parts 60 and 61 abut the panel 10 and the part 42 respectively to lock the angle sections 1 and 2 together. As mentioned previously, all the embodiments of the lintels require means for holding the lower regions of the angle sections 1 and 2 apart.In this Figure 10 embodiment, this means is shown as longitudinally extending wooden batten 62. Also shown here is metal mesh 63 which is wrapped around the end of the horizontal flange 9 and nailed or otherwise secured to the wooden batten 62. This metal mesh 63 on the soffit of the lintel enables plaster or rendering to adhere to the soffit.

In the embodiment shown in Figure 11, it can be seen that the second angle section 2 is similar to that of the embodiments shown in Figures 8 and 10. Furthermore, the first angle section 1 is similar to that in the Figure 10 embodiment, except that the second part 61 of the first angle section 1 continues into a third part 70, which is approximately at a right angle to the second part 61 and extends downwards and towards the panel 10. The part 70 is such as to abut the second part 50 of the second angle section 2. This extension of the first angle section 1 provides more secure interlocking of the angle sections 1 and 2.

Figure 12 shows an embodiment which is similar to that of Figure 10, except that the second part 50 of the second angle section 2 and the first and second parts 60 and 61 of the first angle section 1 are of different dimensions, in order to permit the insertion of insulating members 75 and 76. The insulating member 75 is formed as a sheet, and separates the parts 60 and 61 of the first angle section 1 from the first part 42 and the upper end of the panel 10 of the second angle section 2. The insulating member 76 caps the end of the second part 50 and separates it from the first angle section 1. The insulating members 75 and 76, which may be made from poly(vinyl chloride), provide a thermal break between the two angle sections 1 and 2, and hence can reduce the heat transfer through the lintel from one side to the other side of a cavity wall.The insulating members 75 and 76 could be made as a single sheet-form member. This thermal break construction can be applied to other embodiments of the invention.

The embodiment shown in Figure 1 3 utilises a similar second angle section 2 to that used in the embodiments of Figures 8, 10 and 11. Here, the obtuse upper region 7 of the first angle section 1 has two 900 bends providing a first part 80 and a second part 81. The first part 80 extends upwards and away from the panel 10. While the second part 81 extends upwards and towards the upper end of the panel 10. The parts 80 and 81 abut the inside of the parts 42 and 50 of the second angle section 2, so as to interlock the first and second angle sections 1 and 2.

Figure 14 shows a first angle section which is intended to use with a second angle section as shown in Figure 1 3 and elsewhere. In this embodiment, the first and second parts 80 and 81 of the first angle section 1 are replaced by a single vertically-extending part 90. This part 90 is provided with a series of spaced dimples or projections 91, which when viewed in section have a similar outer profile to that of the parts 80 and 81, so that they can similarly engage the second angle section 2. This arrangement provides the first angle section 1 with an upper end section which can abut all three sides of a triangular cavity defined by the second angle section 2, in a similar manner to the seventh embodiment shown in Figure 11. The use of such projections 91 enable the upper region of the angle section 1 to be formed by a pressing operation, rather than by a bending or rolling operation, which is required for the upper regions of the angle sections 1 of Figures 7 to 13.

Although the projections 91 are conical in Figure 14, they may alternatively be hemispherical or some other shape which will engage both of the parts 42 and 50 of the angle section 2.

Claims

1. A lintel, suitable for use over an aperture in a cavity wall comprising two spaced leaves, which lintel comprises first and second angle sections, each of which comprises a lateral flange for supporting, in use, a portion of a respective leaf of the cavity wall above said aperture, each angle section further comprising an upwardly-extending panel, the two panels having portions which interlock with one another to secure the angle sections together

2. A lintel as claimed in claim 1, wherein a lower region of the panel of the first angle section extends substantially vertically from the flange of the first angle section, and wherein an upper region of the panel of the first angle section is provided with the interlocking portion of that angle section, and is inclined at an obtuse angle to the lower region so as to slope towards the second angle section.

3. A lintel as claimed in claim 1 or 2, wherein the interlocking portion of the first angle section is accommodated in an axially extending cavity defined by the interlocking portion of the second angle section.

4. A lintel as claimed in claim 3, wherein the interlocking portion of the first angle section comprises an upwardly-extending part, which abuts the panel of the second angle section; and a laterally-extending part which extends from the upwardly-extending part away from the second angle section.

5. A lintel as claimed in claim 4, wherein the interlocking portion of the second angle section comprises a first part. which extends downwards and outwards from the panel of the second angle section. and a second part which continues from the first part and extends laterally back towards the panel of the second angle section, with the laterally-extending part of the first angle section overlying the laterally-extending part of the second angle section.

6. A lintel as claimed in claim 4, wherein the interlocking portion of the second angle section comprises a first part which extends laterally away from the panel of the second angle section, and a second part, which is disposed parallel to and below the first part and which extends from the first part laterally back towards the panel of the second angle section to define a lateral slot in which the laterally-extending part of the first angle section is disposed.

7. A lintel as claimed in claim 4, wherein the interlocking portion of the second angle section comprises a first part which extends downwards and outwards from the panel of the second angle section, and a second part which extends downwards and back towards the panel of the second angle section, to define a triangular cavity in which the interlocking portion of the first angle section is disposed with the first part thereof adjacent the panel of the second angle section and the free end of the second part thereof adjacent the junction between the first and second parts of the second angle section.

8. A lintel as claimed in claim 3, wherein the interlocking portion of the second angle section comprises a first part which extends downwards and outwards from the panel of the second angle section, and a second part which extends downwards and back towards the panel of the second angle section, to define a triangular cavity.

9. A lintel as claimed in claim 8, wherein the interlocking portion of the first angle section comprises a first part, which extends upwards inside the triangular cavity at a position adjacent the panel of the second angle section, and a second part which extends downwards and away from the first part at a position adjacent the first part of the second angle section.

10. A lintel as claimed in claim 9, wherein the interlocking portion of the first angle section further comprises a third part which extends downwardly from the second part back towards the second angle section at a position adjacent the second part of the second angle section.

11. A lintel as claimed in claim 8, wherein the interlocking portion of the first angle section includes a first part, which extends upwards and away from the second angle section and a second part which extends from the first part upwards and towards the second angle section with the first and second parts of the first angle section disposed in the triangular cavity adjacent the second and first parts of the second angle section respectively.

12. A lintel as claimed in claim 8, wherein the interlocking portion of the first angle section comprises an upwardly-extending part, which is disposed in the triangular cavity adjacent the panel of the second angle section, a plurality of projections being formed in the upwardlyextending part, which projections engage the first and second parts of the second angle section.

13. A lintel as claimed in claim 1, 2 or 3, wherein the interlocking portions are curvilinear.

14. A lintel as claimed in claim 13, wherein the interlocking portions are not circular as viewed in cross section.

15. A lintel as claimed in any preceding claim, wherein the interlocking portions extend longitudinally of the angle sections.

16. A lintel as claimed in any one of claims 13, 14 or 15, wherein the external surface of one of the interlocking portions substantially correspond to the internal surface of the other interlocking portion.

1 7. A lintel as claimed in any preceding claim, wherein the flange of one of the angle sections has a downturned edge and wherein the flange of the other angle section has an upturned edge.

18. A lintel as claimed in any preceding claim, wherein at least one spacer is disposed between lower regions of the angle sections.

1 9. A lintel as claimed in claim 18, wherein the lower regions of the angle sections are biased together so that the or each spacer is clamped between the lower regions of the angle sections.

20. A lintel as claimed in any preceding claim, wherein one of the angle sections is made of thicker gauge material than the other.

21. A lintel as claimed in any preceding claim, wherein the flange and the panel or at least the lower region of the panel, of each angle section, are perpendicular to one another.

22. A lintel as claimed in any preceding claim, which includes one or more thermally insulating members separating the interlocking portions of the angle sections.

23. A lintel substantially as hereinbefore described with reference to Figures 1 to 5, Figures 1 to 5 as modified by Figure 6 or any one of Figures 7 to 14.

24. A method of building a cavity wall having an aperture therein which method comprises building up inner and outer leaves of the cavity wall on both sides of the proposed aperture, mounting thereon a lintel as claimed in any preceding claim so that one of the angle sections is supported by its lateral flange on the outer leaf of the wall and the other angle section is supported by its lateral flange on the inner leaf of the wall, and then building up the outer and inner leaves over the aperture on the first and second angle sections.